Counting Craters

Counting craters on Mercury is a serious job, as the density of craters on the surface of a planet can be used to indicate its age; the more craters present, the older the surface. Although this technique is commonly used on planetary bodies throughout the Solar System, crater counting on Mercury is particularly challenging. Secondary craters are formed by debris thrown out during an impact, and are often big enough to be confused with primary craters. Their inclusion in crater-counting studies, however, would skew derived age results for a surface, making it appear older than it really is, and so care must be taken when deciding which craters to count, and which to leave out.

Date acquired: November 05, 2012
Image Mission Elapsed Time (MET): 260592647
Image ID: 2897484
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -37.74°
Center Longitude: 194.02° E
Resolution: 117 meters/pixel
Scale: The crater just left of upper center is ~20 km (12 mi.) in diameter
Incidence Angle: 37.9°
Emission Angle: 4.6°
Phase Angle: 38.7°
North is to the right of this image

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington